04-03-1999, 12:05 PM #1rmooreFirehouse.com Guest
"Run Flat" or "ZP" Tire Stabilization
A Thread from Forum Moderator Ron Moore
Run Flat or ZP Tire Technology
I conducted research into the issue of vehicle stabilization and how our crash scene work can be influenced by the presence of tires that "run" without air.
Goodyear Tire Co. and Michelin both produce these specialty tires in various sizes. Goodyear sells them as their "Run Flat" series while Michelin sells theirs as "ZP" tires( Zero Pressure). Typical price per tire is $200, topping out at over $450 per tire for top of the line.
The depth of the sidewall of these tires is between 3" and 5". Sizes fit from 14" to 20" rims. A Run Flat tire on a 17" diameter wheel measures 26" in diameter.
The tires is designed to provide zero pressure mobility in the case of total loss of air pressure, enabling the driver to maintain control of the vehicle and to allow the tire to be serviced in a safe or convenient location or time.
The tubeless ZP or Run Flat tire works without air because of the extreme strength of their sidewalls. They have a normal valve stem and valve core assembly. At full air pressure( 40psi on some tires for example) or at 0 psi air pressure, there is no difference in appearance or depth of the sidewall. The tire WILL NOT go flat.
Run Flat tire technology was introduced in 1992. These performance tires( from Goodyear) are standard equipment on all Corvettes since '96 model year. Neither manufacturer has a whitewall and there are no raised white letters. Goodyear tires do say Run Flat. Michelin tires do say ZP in their size designation; well actually you'd have find it within the small black lettering on the side of the black tire at 3AM, "P205/60R 15 MXV4 ZP XSE RRBL" for example on one variety of Michelin ZP tire.
ZPs or Run Flats are available for vehicles such as Mark 8, Continental, Cadillacs, Porsche, Vette, Trans Am and Ferrari. The 20" Run Flat fits on the Plymouth Prowler.
Here's the catch. Because there is no noticeable difference in the tire with or without air, the vehicle MUST have a remote tire pressure monitoring system installed. Performance cars may have this device factory-installed ( Vette for example). Aftermarket cost for the air monitoring system alone is $300 for a low tech system.
At a crash scene, pulling valve cores, pulling/cutting valve stems, deflating air with tire chucks, or leaving the ZP tire fully inflated will make NO difference in your stabilization effectiveness.
I say, train your troops to stabilize all vehicles sitting on 4-wheels according to your dept's protocols. If it's a Run Flat, so be it. It's easier to standardize our effort for 99.9% of our crashes than to try to make an exception for this ultra high performance tire that we'll find less than 1% of the time.
That's my report...... what do you think?
04-03-1999, 10:27 PM #2ZmagFirehouse.com Guest
My question is, How does the driver know to get to that "convienant" service point if you can't detect the problem? They advertise that you can go 50 miles at 50 mph at zero pressure. But you have no way of knowing that your 50 miles started. Just another hi class frill that only gives us problems.
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